Power Distribution Control Strategy For Photovoltaic Electric Vehicle Charging Station Based On Load Forecasting

With the increasing environmental pollution caused by the consumption of fossil energy,the electric vehicle industry has developed rapidly.At the same time,the operation mode of electric vehicle charging stations(EVCS)has also aroused widespread concern in the society.In order to achieve the goal of no pollution for power generation and no pollution for electricity,the idea,which combines photovoltaic power generation with EVCS to form a micro-grid operation,has gained social acceptance.The thesis takes photovoltaic electric vehicle charging stations as the research object.With the purpose of supply and demand balance and stable operation of charging stations,it studies the operation mode and power distribution control strategy of DC micro-grids containing photovoltaic EVCS on the basis of considering the EVCS load forecasting.First,the load forecasting method of EVCS is studied.According to the 2017 national household travel survey data of the United States,a random trip of the vehicle is constructed based on the Markov chain.The power consumption is estimated by the fuzzy algorithm,and the charging demand is accumulated as needed.The load space-time distribution model of EVCS is established.According to the classification conditions such as family income and place of residence,the factors affecting the load distribution are discussed.Secondly,the DC micro-grid system model considering photovoltaic EVCS is constructed.And the photovoltaic power generation unit,energy storage unit(ESU),power grid supplementary unit and load unit in the system are modeled and analyzed respectively.For the photovoltaic power generation unit,according to the output characteristics of the photovoltaic cell affected by temperature and light intensity,the disturbance observation method is used to achieve maximum power tracking control.For the energy storage unit,the bidirectional DC/DC converter is connected to the DC bus to achieve bidirectional energy flow between the ESU and the DC bus.In addition,In addition,the lack of electricity in the islanding operation of the charging station,the charging station needs to be connected to the grid.The AC/DC rectifier is used to connect the power grid to the bus,so that the 380 V three-phase AC power of the power grid is converted to 600 V DC power.The DC micro-grid system containing photovoltaic EVCS was established.Finally,the power distribution control strategy of photovoltaic EVCS is studied,and the various operation modes of photovoltaic EVCS are analyzed.The traditional power distribution control strategy based on bus voltage achieves regulation by monitoring the voltage fluctuation amplitude after supply and demand imbalances occur,but this method has lag.In order to solve the lag problem of this control method,the power distribution control strategy based on load forecasting is proposed.This strategy can reduce the voltage fluctuations when the operating mode of the charging station is switched,but sometimes it may cause runaway.Therefore,this paper proposes to combine the power distribution control strategy based on bus voltage and load forecasting to form a collaborative control strategy.In the cooperative control strategy,the load forecasting rules reflect the characteristics of advanced regulation,which can optimize the upper limit of the system control time.And the bus voltage rules ensure the lower limit of the system control time.The continuous and stable operation of the charging station is realized.Finally,the effectiveness of the control strategy is verified by Matlab/Simulink simulation and comparative analysis.